Ben,
I lived in SD a long time and loved it. Not sure where you're staying, but here's your to do list, you'll love SD:
Dinner in Old Town (I rec Rockin' Baja Lobster)
Take the trolley from Old Town to the Gaslamp district so you don't have to drive.
Gaslamp is fun if you're 21+, just walk up 5th. Shopping during the day.
Pacific Beach/Mission Beach day or night
TJ is dirty, which is good and bad. At night, go to Avenida Revolucion within walking from border, also check out a bull fight. Mexico during the day isn't bad when the sun is out if you just want some cheap beer. 50 cent coronas anyone?
Drive down the coast of baja, stop in Puerto Nuevo and Rosarito, watch out for Federales.
SD has great golf -- check out Torrey Pines for a fair price, PGA tour stop and 2 kickass 18's.
If you are military, MCAS Miramar has an outdoor aviation museum (old planes) plus F-18s, CH-46s, and CH-53s on the flightline. If you call ahead, you may be able to get a tour and some sim time. NAS North Island is mostly H-60s and S-3s, and sometimes the aircraft carriers are parked there.
McP's Pub in Coronado is a reknown SEAL hangout, owned by a retired SEAL.
The MCRD lets the public watch Marines graduate from boot, great ceremony
Harbor booze cruise, ship called the Hornblower I think.
Hyatt hotel downtown - top floor bar has a good view of the city
Wild animal park is better than the zoo, but it's a drive
Sea World
Girls love La Jolla for shopping, it's like Rodeo Dr by the beach. Stop and sea the sea lions at the "Children's Pool" in La Jolla, better than the zoo in my opinion.
Rent kayaks and kayak in the Pacific or Mission Bay. There are some bars you can almost paddle to. Sailboats also available for rent.
Balboa Park if you're into museums, peaceful crap, and flowers.
The USS Midway is parked in the harbor, but I don't think it's open to the public yet.
Torrey Pines State Park for hiking/beach. Cabrillo Nat'l Monument is a good view.
Hot air balloon rides up near Del Mar, Rancho Santa Fe area. $$$
The Hillcrest area has lots of guys who will buy you drinks, or so I've heard.
If you're coming from Texas, then, by surfing you mean renting 11-foot foam boards and falling a lot??? No offense if I'm wrong, but for beginner surf go to La Jolla Shores or the Mission Beach area. Steer clear of Blacks unless you're decent, especially if there's any size and you can't ride left. Though if you're a beginner, I'm sure the walk down will discourage you. Watch out for Captain One-eyed Willie down there. And I'm not sure where there is surf in Pt. Loma, but perhaps he meant Sunset Cliffs in Ocean Beach. If you're really into surfing, then you already know the good breaks listed in the surf mags. If not, San Diego is great b/c you can just drive up the coast from Ocean Beach all the way to Orange Country and find any number of good spots. PCH is your friend. There are no secret spots in Socal.
I'll second the In 'n Out nomination for eating. A Texas friend of mine compared it to Whataburger... Whatacrockofs..t NOT EVEN CLOSE. Go to In 'n Out and decide for yourself. Fatburger is good too at the end of Garnet in PB.
If you really want the best burrito in SD, go to Papachito's. Dinky little place in a strip mall, but I'll defend their California Burrito against anything. Make sure you try the hot sauce. Their # is 858-452-9446, located on Governor Dr. I'm in Pensacola and I still have their number in my cell phone. Pathetic, really.
Any other questions, just ask. I'm jealous.
Edited to add that The Field in the Gaslamp on 5th is one of the best Irish pubs I've been to. Check the head on your pint of Guinness.